The present invention relates generally to a paper feeding control device supplied to an electrophotographic copying apparatus, a printing machine or the like, and more particularly, to an improvement of a paper feeding control device capable of continuously feeding paper sheets at desired intervals.
For example, an electrophotographic copying apparatus is provided with a paper feeding control device for deliverying paper sheets contained in a paper containing section such as a paper cassette or a paper deck sheet by sheet to feed the same to an image forming section.
In a so-called high speed electrophotographic copying apparatus capable of copying on a relatively large number of paper sheets per unit time, such control has been conventionally exercised that the subsequent paper sheet starts to be fed after a constant time period since the previous paper sheet was fed by assuming that processing of the previous paper sheet was proceeds as planned, so as to increase the copy speed.
However, this control has the disadvantage in that the spacing between paper sheets is decreased, causing a paper jam or causing a delay of paper feed timing of feeding paper sheets to an image forming section (so-called registration timing) if paper sheets which are being fed slip in a conveying path or the ends of the paper sheets which start to be fed are somewhat out of line with each other in a paper containing section.
As the prior art for solving such a disadvantage, such control has been known that ideal time for conveying paper sheets is compared with actual time for conveying paper sheets to feed back the difference therebetween to a paper feed timing in a registration section, as described in, for example, JP-A-59-212340/1984.
In a recent high-speed electrophotographic copying apparatus, however, the capacity thereof is increased so as to allow continuous copying on a lot of paper sheets with the increase in speed thereof. Therefore, a conveying path from a paper containing section to a registration section for feeding paper sheets tends to be longer. In such a high-speed electrophotographic copying apparatus having a long conveying path, however, if paper sheets are continuously fed at constant time intervals as described above, a state occurs in which a plurality of paper sheets exist on the conveying path.
In such a state, the control described in the above described JP-A-59-212340/1984 has the disadvantage of causing a paper jam rather than being advantageous.
The reason for this is that the front end of the subsequent paper sheet which has been already being conveyed may, in some cases, collide with the rear end of the previous paper sheet which temporarily stops in the registration section, while the slip of the previous paper sheet is detected and the paper sheet is stopped once in the registration section to control the paper feed timing.